Duplexing xerographic reproducing machine with a copy sheet reversing station

ABSTRACT

A XEROGRAPHIC REPRODUCING DEVICE CAPABLE OF BEING SELECTIVELY OPERATED IN EITHER OF TWO MODES. THE FIRST MODE INVOLVES THE CONVENTIONAL XEROGRAPHIC REPRODOF ORIGINALS ONTO ONE SIDE OF SEQUENTLY FED COPY THE SECOND MODE IS A DUPLEXING MODE WHEREIN THE SHEETS ARE FED THROUGH AN ALTERNATE PATH TO SEQUENTIALLY AND AUTOMATICALLY PRODUCE PRINTED MATERIAL ON BOTH SIDES OF THE COPY SHEETS. CONVERSION TO THE DUPLEXING MODE   ACHIEVED BY THE ACTUATION OF A SINGLE SWITCH WHICH DIVERTS THE MOVEMENT OF COPY SHEETS WITH FUSED XEROGRAPHIC IMAGES TO A DUPLEXING TRAY. THE ORIGINAL BEING COPIED MAY THEN BE CHANGED AND THE IMAGE BEARING SHEETS, RETAINED IN THE DUPLEXING TRAY, FED THROUGH THE REPRODUCING APPARATUS AGAIN FOR CREATING IMAGES ON THE SECOND SIDE OF THE SHEETS.

"0. 26, 1911 WADRAW HAL 3,615,129

DUPLEXING XEROGRAPHIC REPRODUCING MACHINE WI'I'IL Filed Aug. 12, 1968 A COPY SHEET REVERSING STATION I 8 Sheets-Sheet 1 JOHN W. WAGNER BY \WJOHN -FY TNIRLEY 7-? I ATTORNEYS Oct. 26, 1 971 DRAwE EI'AL I 3,615,129 DUPLEXING XEROGRAPHIG REPRODUCING MACHINE WITH A COPY SHEET REVERSING STATION 8 Sheets-Sheet 2 Filed Aug. 12, 1968 Fla. 3

mvuw'roks WILUAM A. DRAWE JOHN A Jo \MWgNER W H EWgLY ATmR/VEYS United States Patent 3,615,129 DUPLEXING XEROGRAPHIC REPRODUCING MACHINE WITH A COPY SHEET REVERS- ING STATION William A. Drawe and John W. Wagner, Penfield, and John F. Wirley, Webster, N.Y., assignors to Xerox Corporation, Rochester, N.Y.

Filed Aug. 12, 1968, Ser. No. 752,075 Int. Cl. G03g 15/00 US. Cl. 3553 12 Claims ABSTRACT OF THE DISCLOSURE A xerographic reproducing device capable of being selectively operated in either of two modes. The first mode involves the conventional xerographic reproduction of originals onto one side of sequentially fed copy sheets. The second mode is a duplexing mode wherein the copy sheets are fed through an alternate path to sequentially and automatically produce printed material on both sides of copy sheets. Conversion to the duplexing mode is achieved by the actuation of a single switch which diverts the movement of copy sheets with fused xerographic images to a duplexing tray. The original being copied may then be changed and the image bearing sheets, retained in the duplexing tray, fed through the reproducing apparatus again for creating images on the second side of the sheets.

This invention relates in general to continuous and automatic xerographic reproducing machines, and in particular, to improved xerographic reproducing machines capable of continuously and automatically forming images on either one or both sides of sequentially fed copy sheets.

In the process of xerography, as described in U.S. Pat. No. 2,297,691 to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material afiixed to a conductive backing is used to support electrostatic images. In the usual method of carrying out the process, the Xerographic surface is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge the charge in the areas where light strikes the layer. The undischarged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original light pattern.

The latent electrostatic image then can be developed by contacting it with a finely divided electrostatically attractable material such as a powder. The powder is held in image areas by the field of the electrostatic charges on the layer. Where the charge field is greatest, the greatest amount of material is deposited; where the charge field is least, little or no material is deposited. Thus a powder image is produced in conformity with the light image of copy being reproduced. The powder is subsequently transferred to a sheet of paper or other surface and suitably affixed thereto to form a permanent print.

Since the disclosure of the basic concept of xerography, as disclosed in the above-noted Carlson patent, a variety of machines and devices have been proposed to incorporate such teachings in a manner to create copy xerographically on a commercial basis. For the most part, such machines in present commercial use are limited to making a limited number of reproductions from an original. These are 3,615,129 Patented Oct. 26, 1971 ice generally referred to as copiers. Other machines, as for example, that described in Osborne et a1. Pat. 3,301,126, issued J an. 31, 1967, are directed to Xerographic machines capable of use as copiers or duplicators. Duplicators are capable of rapid creation of large numbers of copies from an original. In either instance, however, these prior art machines are usually designed only for the formation of xerographic copy on one side of copy sheets moving through the reproducing mechanisms.

It is therefore an object of this invention to reproduce images on both sides of copy sheets.

It is another object of this invention to continuously and automatically form Xerographic images on both sides of copy sheets.

It is another object of this invention to continuously and automatically form images on one side of copy sheets or, in the alternative, continuously and automatically form images on both sides of copy sheets.

It is a further object of the instant invention to direct copy sheets with images on one side thereof, to exterior of a xerographic reproducing machine, or, in the alternative, direct them to a duplexing station so that they may be refed through the reproducing elements of the machine for forming images on their reverse sides.

These and other objects of the instant invention are achieved by a reproducing machine having a plurality of copy sheet feed paths to permit fused xerographic copy to be moved exterior of the xerographic reproducing machine, or, in the alternative, to permit the fused Xerographic copy to be moved to an internal dupleXing station. From this duplexing station, the copy sheets may be fed through the reproducing elements to create copy on the second sides of the sheets so that the resulting copy sheets contain printed matter on both sides thereof.

For a better understanding of the invention as Well as other objects and further features thereof, reference is had to the following detailed description of the invention which is to be read in conjunction with the accompanying drawings wherein:

FIG. 1 illustrates schematically a preferred embodiment of a xerographic reproducing machine constructed in ac cordance with the instant invention;

FIG. 2 is a schematic illustration of the machine as shown in FIG. 1 but includes various timing switches;

FIG. 3 is a front view of the control panel of the xerographic machine; and

FIGS. 4a, 4b, 4c, 4d, 4e and 4] are schematic electrical diagrams of the electrical components of the xerographic machines.

As shown schematically in FIG. 1, the automatic Xerographic reproducing apparatus comprises a Xerographic drum-shaped surface 10 including a photoconductive layer or light-receiving surface on a conductive backing. This surface is mounted on a shaft 12 journaled in a frame to rotate in the direction of the arrow to cause the drum surface sequentially to pass a plurality of Xerographic processing stations.

For the purpose of the present disclosure, the several Xerographic processing stations in the path of movement of the drum surface may be described functionally as follows:

A charging station A at which a uniform electrostatic charge is deposited on the photoconductive layer of the Xero-graphic drum;

An exposure station B, at which alight or radiation pattern of copy to be reproduced is projected onto the drum surface to dissipate the drum charge in the exposed areas thereof and thereby form a latent electrostatic image of the copy to be reproduced;

A developing station C, at which a xerographic developing material including toner particles having an electrostatic charge opposite to that of the electrostatic latent image are cascaded over the drum surface, whereby the toner particles adhere to the latent electrostatic image to form a xerographic powdered image in the configuration of the copy being reproduced;

A transfer station D, at which the xerographic powder image is electrostatically transferred from the drum surface to a transport material or drum surface; and,

A drum cleaning and discharge station E at which the drum surface is brushed to remove residual toner particles remaining thereon after image transfer, and at which the drum surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.

The various charging functions are carried out by corotrons positioned around the periphery of the drum. These include the charging corotron 14, the transfer corotron 16 and the neutralization corotron 18.

The optical image is projected onto the rotating drum from a support member which consists of a transparent curved platen on copy board 20 illuminated by banks of suitable lamps LMPs. The image on the copy board is scanned by an oscillating object mirror 22 and projected through a fixed lens 24 and reflected from a fixed image mirror 26 to a fixed light shield 28. The timed relationship between the object mirror 22 and rotation of the drum permits the dissipation of the charge on the photoconductive surface to correspond to the image being reproduced.

The primary path of travel for copy sheets to receive toner powder images transferred from the drum includes suitable sheet feeding elements housed in a sheet forwarding assembly 30. This assembly acts to sequentially forward sheets to the bottom of the first or A transport 32 which is a vacuum conveyor. A first set of stop register fingers RSl acts to align and temporarily stop the leading edge of each copy sheet to thereby permit it to be moved into contact with the rotating drum in alignment with the toner image to be transferred. After transfer, the copy sheet is removed from the drum and transported by means of the second or B transport 36. Next in line in the primary paper path are the fuser rolls 38 and 40 which affix the toner image to the copy sheet for creating a permanent copy. The next conveying element is the third or C transport 42 which moves the copy sheet to an elevated location for depositing it in the copy catch tray 44 associating with exterior of the xerographic reproducing machine.

Insofar as has been described, the above-described xerographic reproducing elements are substantially the same as that disclosed in the aforementioned Osborne et al. patent.

According to the instant invention, however, an alternate copy sheet path is provided. The alternate path includes a pivotable deflector plate 46 positioned between the fuser rollers 38 and 40 and the C transport 42. As shown in the dotted line position of FIG. 1, the plate is positioned to permit copy to pass thereover and deposit it in copy catch tray 44. When, however, it is moved by the solenoid SOL-1D into the solid line position of FIG. 1, it will deflect the copy sheet with fused images past a first pair of guide plates 48 onto a third or D transport belt 50, and into contact with initial guide plate 52 and then into duplexing tray 54. It is then possible after the predetermined number of copy sheets has been fed through this path into the duplexing tray 54 to sequentially feed these sheets through the xerographic reproducing cycle once again for creating images on the reverse side thereof.

As sheets with fused images on one side thereof, are entering the duplexing tray 54, pivot fingers 56, operable off of solenoid SOL-4D, are in an activated position extending through the feed belts 58. Pivot fingers 56 guide the leading edges of copy sheets entering the duplexing tray and prohibit them from contacting and binding on the friction surface of the belts 58. After the run of sheets has entered the tray, the fingers 56 retract so that the sheets can rest in facing contact with the belts for being sequentially refed through the xerographic transfer and fusing stations.

Depressing the START-PRINT" button during the machines duplexing mode activates solenoid SOL-5D to energize the belts 58 to feed the sheet in contact therewith upwardly. This depression of the START-PRINT button also allows solenoid SOL3D to be periodically tripped to urge pressure fingers 60 into contact with the sheets being fed so that good frictional contact can be made between the belts 58 and the sheet in contact therewith. SOL3D is operable off of limit switch 28LS on the main cam bank of the machine.

Rotation of the belts 58 also rotates the lower feed rolls 62 and 64 to feed the sheet through the lower guide plates 66, through upper feed rolls 68 and 70, through upper guide plates 72 and into contact with the A transport 32. At this point the sheet is in the conventional feed path corresponding to the non-duplex mode. It can then be fed by the A transport 32, into contact with the first stop register fingers RS-l for receiving transferred toner images by conventional feeding through the xerographic transfer station D.

As the first sheet is fed from the duplexing tray 54, its leading edge trips limit switch XLS between the upper and lower pinch rolls and the conventional limit switch 27LS on the A transport. The tripping of 27LS at this time acts to separate the continually rotating upper pinch rolls 68 and 70 to prevent the feeding of the following sheet. The separation of these rolls also acts to bring a set of supplemental register stop fingers RS2, adjacent the upper guide plates 72, to interfere with the motion of the following sheet and align its leading edge as it awaits its signal to be fed through the xerographic transfer station after the previous sheet.

The sheet being held by stop register fingers RS2 is released at the proper time by the influence of a newly provided limit switch 36LS on the machine cam bank. Actuation of 36LS moves the register fingers RS2 out of interfering contact with the sheet and de-energizes solenoid SOL-2D to close the rotating upper pinch rolls 68 and 70 to drive this sheet into contact with the A transport and primary stop register fingers RS-l in the conventional non-duplexing manner. Actuation of 3615 also reactivates the solenoid SOL-5D to yet feed a third sheet from the duplexing tray 54 so that this third sheet can move up to the stop register fingers RS2 to replace the sheet previously fed out into contact with the primary stop register fingers RS-l. The limit switch 27LS acts to trip the solenoid SOL5D to remove power from the belts 53 and lower feed rolls 62 and 64 so long as the sheet being brought from the duplexing tray 54 has advanced far enough that it trips limit switch XLS. If the following sheet should be advanced late from the duplexing tray, it will continue to be fed upwardly until it trips XLS.

As can now be understood, this feeding of sheets for the duplexing mode continues in a sequential manner until all of the sheets are fed. Termination of the duplexing sheet feeding operation is accomplished by copycount coincidence being reached between the number of sheets dialed on the programmer and the pulsation of the programmer as counted by 27LS.

The control panel of the apparatus as shown in. FIG. 3 is also substantially the same as that described in the aforementioned Osborne patent. There is, however, a modification in the lower righthand corner thereof. This modification includes a DUPLEX ON switch and a DUPLEX OFF switch and a pair of lamps LMP-Sl and LMP-SZ marked DUPLEX SIDE 1 and DUPLEX SIDE 2 respectively. The SPECIAL DOCUMENT light has been removed from the disclosed Osborne et al. machine along with its accompanying function.

In order to operate the machine in the conventional non-duplexing mode, the operator merely depresses the DUPLEX OFF switch, dials the desired number of copy sheets on the selector knobs 81A, 82A, and SSA with the POWER ON switch depressed and then presses the START PRIINT button. The dialed number of copies of the original are then created and fed out into the copy catch tray. -When, however, an operator wishes to run the machine in the duplex mode, he will operate in the same manner as before, but, instead of depressing the DUPLEX OFF switch, he will depress the DU- FLEX ON switch. Then with the power on and the number of copies dialed on the selector switches, the depression of the START PRINT button will cause the dialed number of copies to be created and fed into the duplexing tray 54. After the machine has detected coincidence between the copy count indicator and the dialed number of copy sheets, the lamp LMP-Sl behind the DUPLEX SIDE 1 indicator will become inactivated and will illuminate LMPASZ to indicate that the machine is ready to begin creating copy on the reverse sides of the copy sheets in the duplexing tray.

The operator may then take the original document off the platen member 20 and replace it with another document, the contents of which are desired to be reproduced on the opposite side of the cop'y' sheets. The depression of the START BRINT button will then refeed the copy sheets from. the duplexing tray through the xerographic transfer station to form the powdered image on the reverse side of the copy sheets. Further movement through the fuser and along the C transport 42 will deposit the copy sheets into the copy catch tray with xerographic reproductions on both sides thereof. The sheet feeding elements adiacent the duplexing tray will continue to feed all of the copy sheets therefrom. until coincidence is again reached between the copy count indicator and the preselected dialed number of copies.

The programmed operation of the various mechanisms which are used to control the non-duplex mode as well as duplex functions which are substantially the same to the non-duplex mode are controlled by circuitry as shown in FIGS. 40, 4b, 4c, and 4d. These electrical schematics are substantially the same as those shown and described in the aforementioned Osborne patent. Various parts of the circuitry, however, have been removed since their functions are no longer necessary, desired or expedient. For example, the interlocked circuits and abort circuit have been removed.

Furthermore, a. duplexing drawer interlodk limit switch DLS has been added to the circuit to insure that the machine cannot operate unless the drawer housing containing the D transport 48 has been slid into the machine. These elements have been made slidable on a drawer for clearance in the event of a paper jam in this region in a manner similar to the B transport drawer mounting described in the aforementioned Osborne patent.

The circuitry on FIGS. 4e and 4 are supplemental t0 the circuitry of FIGS. 4a, 4b, 4c and 4d to accommodate the duplexing functions. FIG. 4] may generally be referred to as the duplexing standby circuit.

'In order to operate the machine, the power-on button must first be depressed to bring the fuser temperature up to an operational degree. The operator would then press either the duplex-on or duplex-off button depending on the mode desired to be made. The machine will remain in the mode that it was last operated. If it is desired, for example, to make a duplex run, and the machine was last run in the non-duplex mode, the DUPLEX ON button would have to be depressed. When operating in the duplex side 1 mode, SOL-4D is not energized. Therefore, fingers 56 extend through belts 58 to guide copy sheets entering the duplexing tray 54. During the duplex side 2 operations, however, 2YCR1 closes, energizing SOL-4D to withdraw fingers 56 out of contact with the sheets in the duplexing tray so that the sheets being fed may make full face contact with rotating belts 58. Contact 1YC-R3B is used when operating in the duplex side 1 mode to ensure that the pinch roll solenoid S'O L2D remains deenergized during duplex side 1 operations. Without this, IWOR would be opening and closing during duplex side 1 operations.

The depression of the DUPLEX ON switch, which is connected to line 147, pulls in relay XOR-1, which has three contacts. Pulling in relay XOR sets up the circuit for the standby duplex circuit. .As its first contact XOR-1 closes, it pulls in relay IYCR and ZYOR. Contact 1YC=R1 is the holding contact for the IYOR and ZYCR coils to keep them energized after the programmer reaches coincidence and TCRZ is opened. This closes contact lYCtR- 2A to light lamp LMP-S1 to indicate we are ready to operate in the DUPLEX SIDE 1 mode. It also opens contact 1YOR-2B to retain lamp LMP-S2 unilluminated and the DUPLEX SIDE 2 indicator off. The closure of the DUPLEX O switch also sets up the duplexlng circuit shown substantially in FIG. 42 by closing XOR-2. Contact XOR-3 prevents reprinting until the machine has timed out through the normal course of operation.

T he closing of lYCR closes lYCR-3A setting up the circuit to the divertor solenoid SOL-1D to raise the divertor plate 46 and thereby direct sheets onto the duplexing transfer 50. This also opens the circuit to the upper feed roll and stop register fingers RS-2 via its control solenoid SOL-2D adjacent the duplexing paper feeder. This solenoid allows rotation of pinch rolls 62 and 64 and permits the separation and closing of the upper pinch rolls 68 and 70. Closing of 2YCR also opens 2YC-R1 to prevent power from entering the duplex paper feeder circuit at this time. With the machine in the duplex side 1 stage we are now ready to copy on the first side of sequentially fed copy sheets.

The operator now presses the START PRINT button SW- 4 in the normal mode of operation. The first thing that happens insofar as duplex side 1 is concerned, is that we supply power to the divertor solenoid SOL-1 so that the divertor plate 46 will direct copy sheets onto the duplexing transport 50 and into the duplexing tray 54. This also acts to feed copy sheets in the normal mode of operation through the xerographic transfer station D until the number of sheets passing 8LS and the transfer station D causes the copy count indicator to reach coincidence with the programmer STR with the preselected number of sheets to be printed.

Once coincidence has been made, relay RCR will be picked up. This serves two functions. The first function is to provide the normal functions of 7CR (FIG. 40) which is to be used in series with the programmer STR to provide shutdown for the machine. In this duplex-side 1 mode we start to time out our machine via relay contact RC-Z which is connected to line 108 and the 7CR coil. The picking up of RCR also energizes a mechanical latching relay TCR into its alternate position. When we pull in the mechanical latching relay TCR, this in turn serves two functions. It picks up relay SCR which has a contact SCR-1 in series with the relay IYCR and ZYCR coils. Picking up relay SCR1 does not do anything immediately because there is, in parallel therewith, as a holding circuit for lYCR and 2YCR, the 2TR-4 timer. This delay gives us the ability to be able to get paper all the way through the divertor chute after coincidence has been achieved before '2TR-4 opens, dropping out relays LYCR and ZYCR which set up the circuit for duplex side 2 mode.

After completion of duplexing side 1, the machine automatically reverts to a duplex side 2 mode. Immediately upon the reaching of programmer copy count coincidence, 4CR-3 drops out. This would remove power from the lower duplex paper feeding elements 4670. However, the ZYCR-l contact has normally gone closed after 4CR-3 is open. Therefore, the paper feeding elements adjacent the duplexing tray 54 are inactivated at this time. In any event no power is being supplied to the paper feeder during the timing out of side 1.

While on standby we have the DUPLEX SIDE 2 light lit but the sheet feeding elements are inactivated. The operator may then change documents on the platen 20 so that new material may be printed on the reverse side of the copy sheets. The operator repressed the START PRINT button. This will set up the circuit to the bottom feeder by closing again 4CR-3 which supplies power to the bottom paper feeder.

This will immediately energize the paper feeder solenoid SOL-D which drives the belts 58. It also acts on the finger solenoid SOL-3D to cause the fingers 60 to put pressure on the face of the paper to increase the pressure between the paper and the belt for feeding a single sheet. The sheet feeding elements beneath the A transport 32 act to move a single sheet from the duplexing tray 54 into contact with lower rollers 62 and 64, and through the plates 66 into contact with the upper rollers 68 and 70. 1WCR-2, in series with the upper drive roll solenoid SOL2D operates to actuate that solenoid. At this startup time, the solneoid SOL2D is deenergized and the upper drive rolls are closed.

The sheet feeding assembly in general acts to sequentially drive single sheets up to the A transport 32 where it is fed past limit switch 27LS. Upon contacting 27LS, relays IWCR and 2WCR are pulled in. The function of 1WCR is to close the SOL2D circuit to separate the upper drive rolls. 1WCR-1B will remove power from the clutch SOLSD and finger solenoid SOL-3D. It will also remove power from the primary rectifier circuit PRC-1 unless we do not have a second sheet in the lower rolls 62, 64. Limit switch XLS is located just in front of the lower rolls so that the conveying elements and their actuator SOLSD will remain energized and get the second sheet of paper up just in front of the pinch of these rolls into contact with XLS. In this location the next sheet is ready to be fed up to the A transport 32.

Switch XLS is located in series with a relay VCR. VCR keeps power out of the primary rectifier and also, when energized, it will remove power opening the finger solenoid SOL-3D circuit. When we have the second sheet in position above the lower feed rolls 62, 64 awaiting the feeding of the sheet in front of it, we have relay contacts 1WCR-1B open, VCR1 open, ZCR-'2 open, and no power in the paper feed circuit.

The next step is to move the paper from the A transport 32 into the transfer zone D in synchronism with the rotating image on the drum I0. This registration is accomplished by a cam switch 36LS on the cycling switch bank of the machine. Contact 1WCR1A sets up the circuit to relay ZCR when switch 27LS is closed by being contacted by a copy sheet. This energizes IWCR and, thereafter, relay ZCR is picked up through 36LS, the timing switch on the machine cam bank. The conventional non-duplexing mode employs 5LS which is also on the conventional cam bank. In the duplex mode the switch 36LS is em ployed to compensate for the different traveling distances of sheets to stop register fingers RS4 in the different modes. The switch 36LS is a momentary switch which, when actuated, indicates that the drum is in registration with the paper waiting on the A transport. 36LS will pull in relay ZCR which holds itself in with ZCR-l, ZCR-2 supplies power to the primary rectifier circuit again causing the belt 58 to drive and the fingers 60 to depress the next paper into contact with the belt. Actuation of ZCR also actuates ZCR-3, which is in series with the upper drive pinch rolls 68 and 70, solenoid SOL2D causing 8 these rolls to close and drive the paper along the A transport to RS-l. This allows the second or following sheet to replace the previous sheet on the A transport against RS2 beyond 27LS for awaiting xerographic transfer.

Another switch, 2815 is also added to the circuit in parallel with VCR-2. The function of 28LS is to assure that we bring fingers 60 into pressing contact with the belt at the same time of each cycle. If we did not have this 2.8LS, and depend merely on XLS to provide the timing to the pressure finger solenoid SOL-3D, we would have variations in the times that papers were transported up- Wardly by belts 58 due to timing variations caused by the mechanical fingers and belts.

If the duplexing sheet feeding elements fail to convey the sheet onto the A transport 32 and into the xero graphic transfer station D an image is still formed on the drum but does not get transferred to a copy sheet. This does not affect the coincidence count since no sheet has been fed to trip 27LS.

When coincidence is reached, relay RCR is picked up to serve two functions. It closes contact RCR2 which starts the shutdown circuit by energizing relay 7CR. It also closes RCR-1 to energize the latch relay TCR. This puts us back into the duplex side 1 condition again by deenergizing relay SCR. The opening of TCR-1 drops out IYCR and ZYCR after a time delay since SCR does not get deenergized until line W-42 goes dead through machine time out. Note that relay SCR is connected to line 42 through TCR-1 and SCR-2. This mode of operation is desirable since we do not want to put the divertor solenoid SOL-1D down and send the duplexed copies back around into the duplexing tray. Thus we delay the switching of the divertor plate 46 until coincidence is again reached.

TCR2, connected in series with IYCR and ZYCR, is used to ensure that we remain in the duplex side 1 when the latch relay TCR is in that position or in a standby position. SCR1 would normally close during standby, but the latch remains open because it is a mechanical latching relay and stays in the position in which it was last left.

The previously discussed limit switch 27LS is connected to line WK rather than line W47, for counting the duplex side to copy-count into the programmer. This counting is done on the pulsation of 27LS. As a sheet passes over it, IWCR-3 closes and feeds pulses into the programmer for counting until the copy-count indicator goes to zero again. 2WCR-2 ensures that we keep power on the duplex side two elements after reaching coincidence util the last sheet has entered the primary stop register fingers RS-l of the machine. This is necessary since 4CR- 3 drops out immediately upon the reaching of coincidence. ZYCR-Z prevents the double counting of pulses into the programmer during the duplex side 1 operation.

The stop-print button, as We have modified the circuit now merely energizes relay 7CR to shut the machine down as desired. It does not effect our duplex mode of operation because we change from duplex side 1 to duplex side 2 by using relay RCR in conjunction with latch relay TCR which is not in the programmer of the basic machine of the aforementioned Osborne Patent. Thus the relay RCR remains in the condition in which it was last left. We also have a relay IXCR-3 in contact with the START PRINT button which prevents the operator from pushing the START PRINT button during a time-out cycle in the duplex mode until the operation has been completely timed out.

As can be understood, the above described xcrographic apparatus is capable of moving sheet material along a sheet feed path, from the sheet supply station to the sheet receiving station. Along the sheet feed path, a first conveyor brings the sheet material into a position for receiving transferred toner images from a Zcrographic surface. The sheet may then be directed to either a second or third conveyor. The third conveyor will transport the imagebearing sheets to the sheet receiving station. The second conveyor will transport the image-bearing sheets to a duplexing station which effectively reverses their orientation for supplemental movement past the Xerographic transfer station. After receiving the additional transferred toner images on their second sides, the sheets are transported by the third conveyor to the sheet receiving stations. The various above described control means ensure that the sheet material will be moved along the sheet feed path by the proper conveyors for effecting the creation of copies in accordance with the mode of copying selected by the operator.

While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby; but it is intended to cover the invention broadly within the scope of the appended claims.

What is claimed is:

1. In a Xerographic reproducing machine of the type having a photoconductive member, charging means to impose a uniform electrostatic charge on the member, exposure means to dissipate the charge onto a latent electrostatic image corresponding to an image to be reproduced, developing means to bring transferable toner particles into contact with the member to render the latent electrostatic image a transferable toner image, first conveyor means to move a copy sheet along a sheet feed path from a copy sheet supply station at one end of a sheet feed path into contact with the member in registration with the toner image thereon and then beyond, transfer means along the sheet feed path to transfer the toner image from the member to a sheet and fusing means along the sheet feed path beyond the transfer means to aflix the toner image to a sheet, the improvement comprising a sheet receiving station at the end of the sheet feed path remote from the sheet supply station,

a sheet deflector means positioned on the sheet feed path between the transfer means and the sheet receiving station,

second conveyor means to move a sheet from the deflector means to the sheet receiving station,

a sheet receiving duplexing station located remote from the portion of the sheet feed extended path between said sheet supply station and said transfer means capable of receiving, storing and then feeding a sheet therefrom back toward the transfer means,

third conveyor means to convey a sheet from the deflector means to the duplexing station, and

first control means to selectively control the position of the deflector means so as to convey a sheet to either the sheet receiving station when oriented in a first position or to the duplexing station when oriented in a second position.

2. The apparatus as set forth in claim 1 wherein the fusing means is positioned between the deflector means and the transfer means.

3. The machine as set forth in claim 1 and further including fourth conveyor means to convey sheets from the duplexing station to the first conveyor means and again to the transfer means to thereby transfer an additional toner image to the sheet but on the side thereof opposite from the side supporting the originally transferred toner image.

4. The apparatus as set out in claim 3 and further including second control means to terminate the feeding of sheets from the supply station after the feeding of a preselected number of sheets whether the deflector means is in either its first or second position.

5. The apparatus as set forth in claim 4 and further including third control means to retain the deflector gate in the first position after the termination of the feeding of the preselected number of sheets if the deflector gate 10 is in its first position while sheets are being fed from the supply station but to move the deflector gate from the second position to the first position before the subsequent feeding of sheets from the duplexing station if the deflector means is in its second position while sheets are being fed from the supply station.

6. The apparatus as set forth in claim 5 and further including fourth control means to actuate the fourth conveyor means only after the termination of the feeding of the predetermined number of sheets and only after the deflector means has been moved from its second position to its first position.

7. The apparatus as set forth in claim 6 and further including fifth control means to inactivate the fourth conveyor means after the feeding of sheets therefrom coincident in number with the number of sheets fed into the duplexing station from the supply station immediately prior thereto.

8. In a Xerographic reproducing machine of the type having a photoconductive member, means to create a latent electrostatic image on the member, developing means to bring transferably toner particles into contact with the member to create a transferable toner image on the member, transfer means to transfer the toner image from the member to a copy sheet, fusing means to affix the toner image to the copy sheet, a copy sheet supply station and a copy sheet receiving station, the improvement comprising first conveyor means to move copy sheets from the copy sheet supply station to the transfer means for the transferring of toner images onto the first sides of the copy sheets,

second conveyor means to convey the copy sheets with the toner images from the end of the first conveyor means back to the first conveyor means at a point in advance of the transfer means for a second conveyance by said first conveyor means past the transfer means for transferring toner images onto the copy sheets,

third conveyor means to move the copy sheets from the first conveyor means to the copy sheet receiving station, and sheet retaining means adjacent the second conveyor means adapted to receive and retain a plurality of toner image-bearing sheets and then sequentially feed the plurality of copy sheets therefrom in a reversed orientation so that the second movement of the copy sheets past the transfer means allows the transfer of toner images to the sides of the copy sheets opposite from the sides receiving the first toner images. 9. The apparatus as set forth in claim '8 and further including a sheet deflecting member positioned between the first conveyor means and the second conveyor means, and

first control means operable to vary the orientation of the deflector means so that copy sheets fed therepast may be either moved onto the second conveyor means or the third conveyor means.

10. The apparatus as set forth in claim 9 wherein the sheet retaining means includes a copy sheet receiving tray for receiving copy sheets moved onto the second conveyor means and for retaining the copies until a predetermined number of copy sheets have received toner images on one side thereof.

11. The apparatus as set forth in claim 10 and further including second control means to ensure that the deflector gate is in a position to direct sheets to the third conveyor means while sheets are being fed from the sheet retaining means to the transfer means.

12. The apparatus as set forth in claim 9 wherein the fusing means is positioned between the sheet deflecting member and the transfer means.

(References on following page) References Cited UNITED STATES PATENTS Yohn 27165X Caps et a1 355-26 Teutsch 35514 Aser et a1 3553 X Beckrnan, I r. et a1 2713 Carlson 3553 12 FOREIGN PATENTS 1,185,994 1/1965 Germany 27165 SAMUEL S. MATTHEWS, Primary Examiner K. C. HUTCHISON, Assistant Examiner US. Cl. X.R. 

